A laser machining cell aiming at automatic laser machining by equipping a laser machine and a work transfer device has been put to practical use.
A laser machining system which adds to this laser machining cell, a stacker crane for transferring pallets with work loaded, and a stack yard for storing the pallets could maintain the automatic machining for a long period of time and its productivity is quite high.
In this type of system, the blank work-piece of the loading station is provided to the laser machine by the work-piece transfer device. Following machining, is the work-piece transferred by the work-piece transfer device to the unloading station provided on the opposite side of the loading station to the laser machine.
The machined workpiece is sent to the unloading station, and is parted by the operator on the unloading station.
Because the machining is done automatically, this sorting operation has to be done each time the work is sent to the unloading station. Otherwise, unsorted work is piled on the unloading station making it necessary to stop the laser machining. Therefore, it becomes difficult to carry on the automatic manufacturing. Japanese laid-open patent application Showa 60-247422, Japanese utility model publication Heisei 3-47701 and Japanese laid-open utility model application Heisei 3--36328 disclose metal plate machining system which includes a metal plate machine like a punching press or a shearing machine, a stack yard, and a stacker crane.
Japanese laid-open patent application Heisei 3-196947 discloses a plate machining system including a stacker crane which transfers blank plate to more convenient stack in a stack yard during idle time.
Japanese laid-open patent application Showa 58-93528 discloses a transfer press system including a conveyer which transfers a pallet with blank plates thereon from a stacker crane press machine.
In these systems, a plate worked by a machine (post-worked plate) is always unloaded.
In some case, a remaining part of a post-worked plate can be used again as a pre-worked plate for a future machining.
In a laser machining system including a returning device which returns a post-worked plate to a stack yard, the post-worked plate can be recycled to improve productivity. And, by returning post-worked plate to the stack yard automatically, prolonged, uninterrupted automatic operation can be achieved.